With increased use and decreasing availability of petroleum supplies, gasification technologies of economical solid and high boiling point liquid hydrocarbon sources such as, but not limited to tars, bitumens, crude resides, coal, petrochemical coke, and solid or liquid biomass are currently becoming more attractive technically and economically as a versatile and clean way to produce electricity, hydrogen, and other high quality transportation fuels, as well as convert these hydrocarbon sources into high-value chemicals to meet specific market needs. Currently there are abundant worldwide supplies of coal as well as a large market supply of petrochemical coke in the U.S. market. High boiling point liquid hydrocarbons, such as tars, bitumens, crude resides are also in great abundance and are expensive to upgrade by conventional refining technologies into useable liquid fuel sources. The vast majority of these supplies may be utilized to fuel liquid or solid fired electrical plants in the United States or are shipped oversees as low cost fuels for foreign electrical generation.
However, with current gasification technologies, these hydrocarbon fuel sources can be used to produce significantly more attractive liquid fuels products, such as gasolines and diesel fuels, through the partial-oxidation of these hydrocarbon fuels in a gasifier to produce a syngas product. These solid and high boiling point hydrocarbon feeds, such as tars, bitumens, crude resides, coal, petrochemical coke, and/or solid biomass, contain hydrogen and carbon, and can be partially oxidized at elevated temperatures in the presence of an oxidizing gas or vapor, such as air, oxygen, and/or steam to produce a “syngas” product. The chemistry for producing a syngas from hydrocarbon sources is well known in the industry and appropriate feeds and operating conditions can be selected to optimize the chemical reactions in producing the syngas.
The produced syngas is preferably comprised of hydrogen (H2) and carbon monoxide (CO). This syngas can then be converted into valuable liquid transportation fuels, such as gasoline and diesel, through various catalytic reforming processes. The most common and well-known of these processes is the Fisher-Tropsch process which was developed by German researchers in the 1920's. In a Fisher-Tropsch process, the syngas is reformed in the presence of a catalyst, typically comprised of iron and/or cobalt, wherein the syngas is converted into chained hydrocarbon molecules. The following formula illustrates the basic chemical process involved in the Fisher-Tropsch reaction:(2n+1)H2+nCO→CnH(2n+2)+nH2O[1]
In conversion processes for the production of transportation fuels, the conditions are generally optimized to maximize conversion of the reaction products to higher boiling point hydrocarbon compounds with carbon contents of about 8 to about 20 carbon atoms. As with the syngas production process described above, various chemical processes for the conversion of syngas into liquid hydrocarbon transportation fuels are well known in the art.
Other processes include the conversion of these disadvantaged hydrocarbon feed into syngas (predominantly hydrogen and carbon monoxide) for use as a “clean fuel” in electrical production. The syngas produced by the process retains a relatively high BTU value as compared to the solid and/or high boiling point hydrocarbon feeds from which it is derived. Especially problematic for clean fuel production can be hydrocarbon feeds that are fossil fuel based (such as tars, bitumens, crude resides, coal and petroleum coke), as these feeds may contain a significant amount of contaminants such as sulfur and/or nitrogen. These contaminants can be damaging to power generating equipment as well as pose environmental emissions impacts on commercial processes. By first gasifying these disadvantaged or contaminated hydrocarbon fuels, these contaminants gasified in the process can be more easily removed prior to be using as a gas fuel for power generation than when in the liquid or solid hydrocarbon. These “clean” fuels can then be used as a combustion fuel for high speed gas turbines or for producing steam for steam driven turbines in the industrial production of electrical power.
The benefit of using these solid and high boiling point hydrocarbon fuel sources is that they are economic fuels relative to low boiling point liquid or gas hydrocarbon fuels, especially when such low boiling point liquid or gas hydrocarbon fuels can compete as alternative fuel sources in the as transportation or home heating fuels. This is also due in part to the often significant contaminants (such as sulfur and nitrogen) that are not easily removed from the solid fuel source, often relenting their use to commercial operations which can remove these contaminants as part of the integrated industrial processes.
One significant problem that exists in the gasification industry is materials that have both high temperature strength as well as high corrosion resistance due to the high temperatures and atmosphere associated in the gasification reactor. The reaction temperatures in modern solid and high boiling point hydrocarbon liquid (or “oil”) gasifier reactors can typically exceed 4500° F. or even 5000° F. At these high temperatures conventional high temperature metallurgies such as high chromium/nickel steels are above their melting point and require cooling and metallurgies at these high temperatures exhibit significant reductions in mechanical strength as well as significantly lower corrosion resistance and erosion resistance.
What is needed in the industry is improved gasifier reactor components that exhibit improved strength, corrosion resistance and erosion resistance under the harsh conditions present in a gasifier reactor.